Makefile: Add build dependencies for rootfs image

When using a custom registry (through REGISTRY variable) not all images
must be already pushed, so make sure we have the right dependencies
listed for rootfs image so they can be built if not present in the
registry.

Signed-off-by: Renê de Souza Pinto <rene@renesp.com.br>

Author: rene

Makefile

@@ -749,9 +749,9 @@ ifdef LIVE_UPDATE
 # Don't regenerate the whole image if tar was changed, but
 # do generate if does not exist. qcow2 target will handle
 # the rest
-$(ROOTFS_IMG): | $(ROOTFS_TAR) $(INSTALLER)
+$(ROOTFS_IMG): pkg/mkrootfs-$(ROOTFS_FORMAT) | $(ROOTFS_TAR) $(INSTALLER)
 else
-$(ROOTFS_IMG): $(ROOTFS_TAR) | $(INSTALLER)
+$(ROOTFS_IMG): pkg/mkrootfs-$(ROOTFS_FORMAT) $(ROOTFS_TAR) | $(INSTALLER)
 endif
 	$(QUIET): $@: Begin
 	./tools/makerootfs.sh imagefromtar -t $(ROOTFS_TAR) -i $@ -f $(ROOTFS_FORMAT) -a $(ZARCH)